Mixed matrix membranes, MMMs, consisting of variable loads of a porous polymer network, PPN, within an o-hydroxipolyamide, HPA (6FCl-APAF, made from the reaction between 2,2-bis[4-chlorocarbonylphenyl)hexafluoropropane, 6FCl, and 2,2bis(3-amino-4-hydroxyphenyl)hexafluoropropane, APAF), have been thermally treated to induce the rearrangement of HPA to a polybenzoxazole (β-TR-PBO). HPA is 6FCl-APAF was loaded with a PPN synthetized, by us, by combining triptycene (TRP) and trifluoroacetophenone (TFAP). Mechanical, thermal and morphological properties of the membranes have been determined.CO2/CH4 selectivity of MMMs decreased slightly both when the PPN load was augmented and when thermal rearrangement took place. The changes in selectivity can be attributed mostly to solubility effects for β-TR-MMMs and to diffusive effects for the © YYYY Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 MMM from neat HPA. CO2 and CH4 permeabilities increased to the 2008 Robeson´s upper bond for an optimal 30 % PPN load both before and after thermal rearrangement.These relatively good permselectivities are explained in terms of compaction, rigidity, fractional free volumes and filling-matrix interactions.

The influence of the spherulite size and distribution on the fracture toughness and Izod impact strength at different temperatures of controlled‐rheology polypropylenes with 0, 154, 402, and 546 ppm of peroxide has been evaluated. As the peroxide content increased, the average spherulite size was enhanced and the distribution width reduced. The fracture toughness and the Izod impact strength were lowered with the peroxide content due to the diminution of the amorphous interconnections among the crystalline regions. Porosity seems to control the fracture behavior for the materials with the highest peroxide content. Besides, a considerable loss of ductility was observed ahead of the stable crack growth zone. Below the glass transition temperature, the impact strength underwent a sudden drop with the temperature, more remarkable as the molecular was higher. The main mechanism of deformation and failure consisted on the formation of crazes, stretch out, and a final collapse through the interspherulitic zones. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

Both metal-catalyzed and organocatalytic transfer hydrogenation reactions are widely employed for the reduction of C=O and C=N bonds. However, selective transfer hydrogenation reactions of C=C bonds remain challenging. Therefore, the...

ABSTRACT:With the aim of improving the performance of conventional proton conducting membranes, systems based on two poly(arylene ether sulfone)s and two elastomers were obtained by heterogeneous sulfonation with chlorosulfonic acid. Subsequently, they were characterized, morphologically and electrically, by techniques such as infrared spectroscopy (FTIR), differential scanning calorimetry, dynamic-mechanical analysis, and complex impedance spectroscopy. From the results, it was verified that the reaction of sulfonation had taken place, as well as that these materials formed incompatible and good proton conducting blends. In addition, the storage modulus and the conductivity were subjected to a statistical design to predict the optimum composition, presenting the best mechanical and conducting proton values and as a consequence the most suitable membrane from the point of view of its application in the field of the fuel cells. Very promising results have been found especially with membranes based on binary blends constituted by thermoplastic/elastomer polymers.

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